Desmond geeald fitz-geeald



(No Model.)

D. G. FITZ GERALD.

INGANDESGENT ELECTRIC LAMP.

No. 286,916. Patented Oct. 16, 1883.

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Inventor ilnonzl/ N. PEYERS. Phclwljlhugnpher. wanin mn. at;

UNITED STATES PATENT OFFICE.

DESMOND GERALD FITZGERALD, OF BRIXTON, COUNTY OF SURREY,

' ENGLAND.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 286,916, dated October16, 1883.

Application filed April 18,1883. (No model.) Patented in EnglandSeptember 8,1881,No. 3,890; in France March 8, 1882,

No. 147,799, and in Belgium March 10, 1882, No. 57,317.

\E aZZ whom it may concern Be it known that I, DESMOND GERALDFITZGERALD, of Brixton, in the county of Surrey, England, have inventeda new and useful Improvement in the Means for Production of a Vacuum inElectric Incandcscence Lamps; and I do hereby declare that the followingis a full, clear, and exact description of the same.

My invention has for its object to produce a more complete vacuum inelectric incandescence lamps by effecting the removal of residualoxygen, and, in some cases, residual nitrogen. To this end I employ asupplementary carbon filament, or a wire which may itself be made ofoxidizablemetal-such as iron or zinc-or be covered with an oxidizablemetalsuch as magnesium or other suitable substance placed within thebulb-a'nd capable of being temporarily thrown into circuit, so that bythe passage 'of the current, after more or less complete exhaustion bythe pump, the carbon filament or oxidizable wire will be heated, andthereby effect the absorption of the residual oxygen, and when magnesiumis employed the residual nitrogen contained in the bulb.

The invention is illustrated in the accompanying drawings, in whichFigure l represents a plan and sectional side view of the neck of a lampprovided with an additional conductor. Fig. 2 is a section of a completelamp, and Fig. 3 is a detail view of the extra or supplemental filamentmounted upon its conductors.

D and E are the usual wire conductors, carrying the light-givingfilament A. Into the neck of the lamp I introduce anotherconducting-wire, M, and upon this wire and one of the otherconducting-wires, D, is mounted the supplemental filament N. By means ofthe conductors D and M a current may be passed through the filament Nwithout going through the light-giving filament A. This extra filament Nmay be formed either of an oxidizable metalsuch as iron or zincin whichcase, when sufficiently heated, it effects directly the abstraction ofoxygen, or it may be of unoxidizable metal-such as platinum in whichcase it may be utilized for raising the temperature of the atmospherewithinthe glass vessel during the process of exhaustion,

Oxygen OthEl "gaseous bOdy may be com pletely effected. Of these methodsI prefer to use iron wire surrounded by a ribbon of magnesium, as shownat P. The length of the iron wire should not exceed one and onehalf inchand the magnesium ribbon may be three fourths of an inch long. While thelamp is under the action of the mercury-pump, a current is passedthrough the filament N of sufficient strength to produce a low red heat,and at the same time external heat may be applied to prevent any of themagnesia formed from cracking the glass should it fall away from theheated wire. When the magnesium has absorbed all the residual oxygen,the connections are shifted to the two main conductors D E, and thecarbon filament A is raised to the required temperature, thus drivingout any secluded gases, which will be carried away by the air-pump. Thesupplemental filament may be again heated and caused to absorb any traceof oxygen that may have been left, and also, as it would appear, someportion of the nitrogen.

What I claim as new is 1. In an electric lamp having main-wire terminalsand a light-giving filament, an additional or supplemental filament andan in dependent electrical conductor for absorbing the oxygen, asdescribed. g

2. In an electric lamp having main-wire terminals and a lightgivingfilament, a supplemental filament and an independent electricalconductor, the said supplemental fila- .ment being formed of or providedwith a material readily oxidized, as and for the purpose set forth.

The foregoing specification of my invention for improvement in electricincandescence lamps signed by me this 14th day of March, A. D. 1883.

DESMOND G. FITZGERALD.

Witnesses:

WM. CLARK, 53 Chancery Lane, London, PaientAgent.

T. W. KENNARD, 53 Chancery Lane, Clerk.

